The use of biological therapeutics to treat a range of medical conditions is becoming increasingly popular in modern medicine. These pharmaceutical compositions may contain an active ingredient such as a protein and a pharmaceutically acceptable carrier or solvent. Proteins are biological molecules that elicit a specific response in the human body, thus the pharmaceutical industry has an interest in using these biomolecules as drugs to cure and manage disease. Protein drugs tend to be unstable as a result of their complex three dimensional structures. The interaction within, and the complexity of this structure means more components can be broken down or denatured, and as protein function depends on this structure integrity, protein drugs are difficult to store and maintain. The formulation of protein based drugs present the challenge of keeping the protein folded during isolation, manufacture, and patient use.
Protein drugs, which can be quickly digested and left useless if taken orally, generally must be given by injection. Proteins are very unstable in the gastrointestinal tract, being hydrolyzed and broken down by its acids and enzymes. The oral bioavailability can be as low as <1% due to the effect that their large size and hydrophillicity has on membrane permeability (MacNally & Park, 1990; Lee, Dodda-Kashi, Grass, & Rubas, 1990). Parenteral administration, which has 100% bioavailability, is usually the preferred method for delivering protein therapeutics.
Also, minimization of manufacturing costs while maintaining protein integrity is of paramount importance. Proteins in pharmaceutical compositions are typically packaged and stored in a lyophilized state to maintain their biological activity. Inherent physical instabilities of the polypeptides including denaturing, deamination, and the formation of soluble and insoluble aggregates have become a problem for the storage and handling of these therapeutics in liquid formulations. Factors such as pH, temperature, ionic strength, physical agitations, and cycles of freeze-thaw often result in the destabilization and loss of biological activity of the proteins. Lyophilization provides the protein in a dried form and involves freezing the protein at atmospheric pressure, removing the water in a low pressure chamber, and collecting the sublimed frozen water on a condenser. However, lyophilization requires more handling, increased processing time, a non-reactive and completely air-tight storage container, a sterile solvent during reconstitution, possibly a separate container for the sterile reconstitution solvent, and complex equipment including a drying chamber, condenser, vacuum pump, refrigeration system, and controller devices. It also must be reconstituted prior to injection, which requires a trained individual and time for the protein to go into solution completely. All of these factors increase the cost of manufacture and difficulty of parentaral administration of protein therapeutics in the powdered form.
Liquid formulation can eliminate the long, expensive lyophilization process in favor of a product that is much simpler for the end user to employ. Liquid formulations can be cheaper to manufacture and preferred by physicians. Unfortunately, any water molecules present tend to foster degradation of proteins. If the tendency towards protein degradation in liquid formulation can be overcome, the cost of protein therapeutics can be substantially reduced.
Accordingly, there is a need in the industry for novel formulations and compositions containing therapeutic proteins which promote the stability and maintain the biological activity of the proteins before administration to a patient.
The present invention addresses previous shortcomings in the art by providing compositions and methods for the preparation, stabilization, and/or storage of polypeptides, particularly therapeutic polypeptides.